The present invention relates to a new and improved grinding method and apparatus and more specifically to an improved steadyrest which is used to support the workpiece during an initial grinding operation in which the workpiece is ground to a first size and during a second grinding operation during which the workpiece is ground to a second size which is smaller than the first size.
Automotive crankshafts having a plurality of crankpins have been ground to a desired size using grinding machines of the general type disclosed in U.S. Pat. Nos. 2,723,503; 2,780,895; and 3,006,118. When the crankpins have been ground, they are measured or gauged to determine if they are out-of-round. If one of the crankpins is out-of-round by an excessive amount, the crankshaft is rejected. However, if one of the crankpins is only slightly out-of-round, the crankshaft is transferred to a second grinding machine where all of the crankpins are ground undersize.
In accordance with known procedures, a crankshaft having an out-of-round crankpin is transferred from the first grinding machine to the second grinding machine to perform the undersize grinding. This is done in order to maintain the set up of the first grinding machine to perform the initial grinding operations on other crankshafts. If the first grinding machine was used to perform the undersize or secondary grinding operation, the set up on the machine would have to be changed from the set up used for the initial grinding operation to the set up used for the undersize or secondary grinding operation. The set up would subsequently have to be changed back to the set up used for the initial grinding operation.
During operation of grinding machines to perform the initial and undersize or secondary grinding operations, the crankpins are supported by steadyrests which may have a construction similar to that shown in U.S. Pat. Nos. 3,076,296 or 3,391,500. These steadyrests are set up to support the crankpin in a known manner during a grinding operation. If the size to which the crankpin is to be ground is changed, the steadyrest must be adjusted to enable it to be used with the different crankpin sizes. It should be noted that these known steadyrests are not easily adjusted between a condition in which they are set to support a crankpin during grinding to an initial size and then to support the same crankpin during grinding to a smaller size.